gsfc photography club beginners class session 2 – camera mechanics
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GSFC Photography ClubBeginners ClassSession 2 – Camera Mechanics
Scott Hull12/3/2013
Agenda
Terms Camera Types Camera Parts Camera Settings Shooting Modes and Scene Modes Lenses Filters Flash Gadgets
Terms ISO (ISO = ASA) (adjustable)
The sensitivity of the CCD sensor chip Aperture (adjustable)
The amount of the lens diameter that you use White Balance (adjustable)
The color correction for the light you are collecting Optical vs. Digital Zoom
Optical zoom is where the lens moves to expand or contract the image
Digital zoom is a marketing tool – basically just cropping Live View
The ability to view the image on the display while you compose the shot
Stops A whole ‘stop’ is a change in the amount of
light by half or double 1/250 sec 1/125 sec 1/60 sec 400 ISO 200 ISO 100 ISO f/4 f/2.8 f/2
Aperture numbers change by a factor of 1.4 Square root of 2, since double the light is 2x
area Area of a circle is π r2 : √2=1.414 is the change
in diameter Most cameras now also use partial stops
Camera Types
“Pocket” Camera
“Point and
Shoot” Compac
t
DSLRDigital SingleLens Reflex
Differences Between Camera Types(in a very general sense)
Pocket Cameras + phones
Point and Shoots DSLRs
Small – shirt pocket Medium – purse Large – carry or camera bag
Snapshots Good snapshots Documentation to artistry
Very weak flash (~10’) Stronger flash (~20’) Internal (~20’) + external
View the monitor only Electronic viewfinder Look through the lensShort range zoom Short to very long
zoomInterchangeable lenses
Very small sensor chip Small sensor chip Medium to 35mm frameAuto focus only Manual focus, but
difficultEasy manual or
autofocusVery lightweight Noticeable weight Noticeable to heavy
weightImages OK for 5x7
printsImages OK for 8x10
printsImages OK for BIG prints
Very inexpensive Reasonably priced Can get very expensiveOften keep it with you Grab and go Requires preparation
Camera Parts
All digital cameras have: Lens Shutter Shutter release Sensor Computer Display screen Battery
Most also have: Viewfinder Built-in flash ¼ - 20 tripod mount
Some Have: Hot shoe Mirror / prism Beam splitter Grip Selection dial(s)
Sensors(size does matter)
• Blue box is 35 mm film frame
• The difference (white area) is the crop factor
Crop Factor
Reported relative to 35 mm film Same focal length lens that was used
on film camera now focuses onto a smaller sensor
The sensor image area becomes expanded when viewing, so it is effectively magnified
Because of this, a 100 mm lens on a Canon APS-C camera gives the same magnification image as a 160 mm lens would on 35 mm film
Camera Settings Shooting Modes Scene Modes Focus Modes Metering/ Exposure Compensation File Type/ Image Quality White Balance Playback A whole book full of others – read that book!
(the User’s Manual)
Shooting Modes Auto
Camera selects everything: aperture, shutter speed, focus, flash - all of it, with no overrides
Usually works, often doesn’t Program
Camera picks aperture & shutter speed; focus can be overridden Aperture Priority
User picks the aperture, camera picks the shutter speed to match Often the preferred go-to mode for experienced photographers
Shutter Priority User picks the shutter speed, camera picks the aperture to match
Manual User gets to/ has to pick all settings
Scene Modes
Portrait Landscape Night
Scene Night
Portrait Sports Indoor Macro
Self Portrait Sunset Fireworks Food Documents Beach/
Snow Underwater
(4 options)
Snow Close-up Museum Backlight Panorama Candle Probably
many more…
A Few Common Scene Modes Sports
Increases ISO, for faster shutter speed Landscape
Chooses narrower aperture, for longer depth of field Portrait
Chooses wider aperture, for short depth of field Night Portrait
Long exposure for background, plus flash for faces Fireworks
VERY long exposure (seconds) – should use a tripod Beach/Snow
Compensates for bright reflections by increasing exposure Night Scene
Increases ISO, for greater light collection, no flash
Focus Modes Autofocus on most new cameras is pretty
darned good Even experienced pros are starting to use it
instead of always manually focusing Still not always perfectly crisp Doesn’t work for all situations
Very dependent on high contrast areas Focus point can usually be defined on DSLRs Might still need to tweak the ‘sweet spot’ Manual focus on pocket cameras and point
and shoots is difficult, if possible
Metering Average
Original film approach, not used much anymore Multi-zone metering (aka Matrix, ESP, other names)
Most commonly used default mode Mysterious algorithms consider many factors including
focus point, light distribution, etc. Center-weighted average
Central portion represents most of the input Spot
~1-5% of the field Location is usually definable, often in the center
Use exposure compensation (+/-) to make small adjustments
Files/ Image Quality RAW vs. JPEG
RAW is all of the data, straight from the sensor▪ Largest files, most flexibility later, and highest resolution
JPEG is processed and compressed before saving▪ Losses occur each time it is saved▪ Usually several levels of compression available
Why not just maximize everything with RAW? E-5 Example (12.3 MP camera)▪ RAW file: 12.4 MB, High quality JPEG: 5.3 MB▪ Little discernible loss in image quality until you zoom in▪ In fact, RAW initially looks much noisier at high magnification
Memory cards are big, but not infinite capacity RAW is also not as portable between viewers
White Balance Colors change based on the type of light
Light brown shirt in incandescent light can look green in fluorescent light
Even sunlight vs. shade makes a difference Image is interpreted differently based on settings Auto white balance is pretty good ~98% of the
time Check your display frequently, and change the WB
if necessary RAW images are not corrected, so you can change
it later if it was incorrect Most DSLRs can also set WB manually for unusual
situations
Lenses Built-in vs. interchangeable
Depends on the camera type Fixed vs. zoom
Fixed is typically lighter and has higher image quality Zoom is more flexible
Cheap vs. expensive More expensive lenses have more elements, better
coatings, wider apertures, heavier weight Macro capability
Highly detailed close-up images Teleconverters
Goes between camera and lens to produce 1.4, 1.6, or even 2.0 x the focal length
Zoom Lens Cautions A ‘wobble’ of only 0.03° will cause the image to move by
1/8” at 20 feet With a 50 mm lens, you may not see that With a 400 mm lens, it is 8 times bigger, and very noticeable
Zoom lenses are also usually unbalanced when hand held More likely to get that 0.03° - or more
They also tend to have smaller maximum apertures, so longer exposure times
Tripods help, but faster shutter speeds are more practical Tripod pointing is awkward and slow Faster shutter usually means higher ISO, though more noise
Thus, the driver for more expensive, “faster” zoom lenses
Image Stabilization Uses tiny gyroscopes to detect movement Optical Image Stabilization
Lens shifts the optical path, to stabilize the image Unique to the lens; extra $ for each lens Canon, Nikon, some Sony, Panasonic
Sensor shift Sensor is moved to stabilize image Works with all lenses, even old film lenses Olympus, Pentax, some Sony, Konica-Minolta
Digital Image Stabilization Used in some video cameras Computer changes the pixel region from frame to frame
Performance is rated in equivalent stops improvement Turn image stabilization OFF when using a tripod
Filters Ultraviolet
Mostly to protect the lens Cheap, and nearly invisible in the image
Polarizer Reduces glare Rotate for best effectiveness
Infrared Sees heat, for an ‘other-worldly’ effect
Neutral Density Reduces light, without shifting colors
Color Highlights individual colors
Gradient Neutral density on one end to clear on the other Great for darkening skies
Flash Obviously used to brighten a scene Flash power is determined by the Guide
Number GN = distance x aperture, at a specific ISO Example: 18m at ISO 200 (Olympus E-5 internal) Means that at f/5.6 and 200 ISO, anything beyond
3.2 m (~11 ft) will not be fully illuminated External flash
GN is typically about 30 to 50 Can be moved off-axis, to control shadows Many are remote triggered; can use multiple units
Gadgets Tripod Shutter release Remote control Monopod Camera Bag Lens caps Spare batteries Spare memory cards Reflectors/ diffusers GPS data tagger The list goes on and on…
What next?Now that I figured out my camera and I’m taking great pictures, I have a bunch of pretty files. What can I do with them? Photoshop Elements
If you think they look great now, just wait… Elements has the same basic tools at ~1/10 the price
Prints Costco, Target, Wal-Mart, etc. Probably not worth getting your own printer▪ Usually clog up if you don’t print a lot of pictures
Create a photo book about a subject (cheaper than you think) Online software and Elements both make it pretty easy
Post them online Recommend a Flickr free account Photo Club Flickr site – we want to see what you’ve done! Facebook, other social media
Backup Slides
Exposure ReviewSunny 16 Rule
On a sunny day, at f/16, the shutter speed is 1/ISOStop Action Tripod Zone
11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 100
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
Mor
e D
epth
of F
ield
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Exposure ReviewSunny 16 Rule
On a sunny day, at f/16, the shutter speed is 1/ISOThese ISOs are one stop apart.
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
Mor
e D
epth
of F
ield
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Exposure ReviewSunny 16 Rule – in the shade (-2 stops)
At f/16, the shutter speed is 1/ISO + 2 stops1/100 sec + 2 stops more light is 1/25 sec
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
Mor
e D
epth
of F
ield
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Exposure ReviewSunny 16 Rule – indoors (-4 stops)
At f/16, the shutter speed is 1/ISO + 4 stops1/100 sec + 4 stops more light is 1/6 sec
Stop Action Tripod Zone 11/21/41/81/151/301/601/1251/2501/5001/10001/20001/4000
ISO 50ISO 100ISO 200ISO 400ISO 800ISO 1600ISO 3200ISO 6400
f /22
f /11
f/ 16
f /4
f /5.6
f/ 8
f /2
f/ 2.8
f/ 1.4
Mor
e D
epth
of F
ield
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Pixel Size determines light gathering ability
Camera Pixels
(MP)
Sensor Size (mm)
Sensor Size (pixels)
Pixel Size (µm)
Crop Factor
Nikon D40 6.0 23.7 x 15.5
3008 x 2000
7.9 1.5X
Nikon D200
10.0 23.6 x 15.8
3872 x 2592
6.1 1.5X
Nikon D90 12.3 23.6 x 15.8
4288 x 2848
5.5 1.5X
Canon 450D
12.2 22.2 x 14.8
4272 x 2848
5.2 1.6X
Canon Rebel T2i
18.0 22.3 x 14.9
5184 x 3456
4.3 1.6X
Canon 60D
18.0 22.3 x 14.9
5184 x 3456
4.3 1.6X
Olympus E-5
12.3 17.3 x 13.0
4032 x 3024
4.3 2X
Canon A95
5.0 7.14 x 5.36
2592 x 1944
2.8 -----
Canon PowerShot SX150 IS
14.1 6.17 x 4.55
4320 x 3240
1.4 -----
Smaller pixels mean less light, and more noise, especially in low light
RAW vs. JPEG
RAW: 12.4 MB JPEG: 5.3 MB
Olympus E-5; 12.3 MP camera(MD Renaissance Festival, 2011)
Recommended References Your camera User’s Manual – read it!
Download it for easy searching Carry it in your camera bag for reference
Web sites www.penncamera.com www.DPReview.com www.learnmyshot.com www.photoextremist.com
TV show Wild Photo Adventures Magazines
Digital Photo Popular Photography Photoshop Elements Techniques
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